Water Absorption (Cobb) Testing

This process measures the quantity of water that is absorbed by corrugated materials in a given time. Corrugated materials will lose their strength, shape, and function when they’ve absorbed too much liquid. This test helps determine at what level the moisture needs to remain below for the corrugated board and other materials in your packaging to maintain their strength and ability to protect your product.

Water absorptiveness is a function of various characteristics such as sizing, porosity, etc.  This testing procedure basically determines the quantity of liquid absorbed by a sample of any material in a specified time and under standardized conditions. This test is a practical means of determining the liquid absorptiveness or resilience of treated and untreated papers, boards, fabrics and other materials.

Other liquids such as ink, beverages, oil, and water-based solutions may be used instead of water. The roller method is recommended to insure better consistency and reliability that can be obtained by manual blotting or rubbing the specimen.

Package testing and packaging materials testing are important parts of the research and development process. Package evaluation through packaging tests help to ensure that all corrugated board products and new package designs are created specifically to handle real-world situations.


ISO 535

ISO 535: Paper and board – determination of water absorptiveness – Cobb Method.

This specifies a method of determining the water absorptiveness of sized paper and board, including corrugated fibreboard, under standard conditions. It is not suitable for porous papers such as newsprint or unsized papers such as blotting paper or other papers having a relatively high water absorptiveness. This method is not intended to be used for precise evaluation of the writing properties of paper although it does give a general indication of suitability for use with aqueous inks.

TAPPI T441: Water absorptiveness of sized paper, paperboard, and corrugated fiberboard – Cobb Method.

The test describes a procedure for determining the quantity of water absorbed by non bibulous paper, paperboard, and corrugated fiberboard in a specified time under standardized conditions. It is based on studies by Cobb and Lowe, Cobb and other investigators.


Cobb Method Testing Apparatus 
by Gurley Precision Instruments.